Nonimmediate allergic reactions induced by Mesna.

Mesna (2-mercaptoethane sulfonate Na), a drug that alleviates cyclophosphamide (CYC)-induced hemorrhagic cystitis, is frequently used to treat cancer and collagen diseases. A 33-year-old woman presented with high fever during CYC-based induction therapy for systemic lupus erythematosus. Her final diagnosis was mesna-induced drug hypersensitivity.